Field of the Invention
Exemplary embodiments of the present invention relate to an electronic stability control (hereinafter, ESC) system and a method for detecting a fault of a motor freewheeling circuit, and more particularly, to an electronic stability control (ESC) system and a method for detecting a fault of a motor freewheeling switch capable of detecting a fault using a freewheeling switch and a reverse protection switch for compensating for a counter electromotive force generated when an operation of a pump motor is turned off, in the case in which the electronic stability control system performs a pulse width modulation (PWM) control on the pump motor.
Description of the Related Art
Generally, an electronic stability program (ESP) or an electronic stability control (hereinafter, ESC) system are a system which selectively operate front, rear, left, and right clutched wheels to prevent a skid of a vehicle occurring under extremely instable situations like acceleration, braking, or cornering to stably hold an attitude of a vehicle and correct driver's mistakes.
The existing ESC system outputs a pulse width modulation (hereinafter, referred to as PWM) signal of a predetermined duty ratio to drive a motor for the ESC which determines a discharge rate of a hydraulic pump for vehicle braking.
FIG. 6 is a diagram illustrating a circuit configuration having a freewheeling diode and a reverse protection switch for performing the existing PWM control on a motor and an output graph thereof. The output graph illustrates a fault mode in case that a freewheeling diode or a reverse protection switch is disconnected during performing the existing PWM control. As the existing ESC system uses the freewheeling diode for performing the PWM control on the motor as illustrated in FIG. 6, there is no method for finding out a stuck of the diode without driving the motor. That is, FIG. 6 illustrates a source voltage controlling the motor based on the PWM as a waveform and an operation of a circuit which stops the driving of the motor using a reset signal. In this case, the motor is being driven and thus a surge voltage is generated while the freewheeling circuit is turned off. In this case, since a negative surge voltage depending on a current flowing in the motor is larger than the waveform, a motor switch may not also stand the surge voltage.